1. Field of the Invention
The present invention relates to image processing devices, image processing methods, programs, storage media, and integrated circuits for enhancing the feeling of depth and the sense of three dimensions of an image by adding shadow or light to a two-dimensional image.
2. Description of the Related Art
There has been a strong call by users for technology that increases the “feeling of depth” and the “sense of three dimensions” of displayed video in order to display more natural video on the screen of a large screen FPD (flat panel display) device, for example. In response, three-dimensional televisions and the like that utilize the binocular parallax of humans have been proposed, but it has been pointed out that special dedicated glasses are often required, that there is a large degree of dependence on the image, and that the special devices that are required increase costs. At the present time, one of the selling points of large screen display devices is their technology of achieving a three-dimensional effect in the displayed image (video) by smoothing the gradation characteristics or the color characteristics in the display image.
It is clear that humans utilize not only binocular parallax but also monocular information such as color information, saturation, brightness, contrast (color information contrast and brightness information contrast), shadows, gradient of texture, and relative size, in order to perceive depth and three dimensions in two-dimensional images.
One conventional technology that utilizes such monocular information is the technology of creating a three-dimensional image by detecting the lighting direction and then adding to the input image a filtered image (shading image) that corresponds to the lighting direction that has been detected (for example, see JP 2003-196639A).
FIG. 85 is a block diagram that shows the configuration of this conventional image processing device (three-dimensional device) 9000.
First, when an input image (input image signal) is input to a creation portion 5001 of the image processing device 9000, a plurality of filters with a filter coefficient that have been readied in order to detect a lighting direction are applied to the input image signal to create filtered images (shading images). The image processing device 9000 determines that the light (lighting) is coming from a filter direction that corresponds to the filter coefficient with the smallest average difference between the pixel value of the filter processed image and that of the input image. In the image quality improvement portion 5002, the filtered image that corresponds to the lighting direction that has been determined is subjected to noise removal processing (processing by a noise removal portion 5003) and dispersal processing in all four directions (in the image) (processing by a shake portion 5004). Next, the gain rate that is obtained by a gain adjustment portion 5005 is multiplied with the filtered image, and the output that is obtained from this multiplication is added to the input image by an adding portion 5006. The output of the adding portion 5006 is processed by a mapping portion 5007 and output from the image processing device 9000. The image processing device 9000 outputs the image obtained in this manner, creating a three-dimensional image. It should be noted that in the image processing device 9000, filters for extracting borders in a plurality of directions have been readied as the filters that correspond to the various lighting directions. Further, it is possible to add three dimensionalness by diffusing the value of the filtered image in all directions (on the image). It should be noted that in the image processing device 9000 it is expected that the detection processing is performed under the assumption that the light (lighting) is coming from a single direction, and thus the coefficients of the filters that correspond to these directions are prepared in advance.
In the above conventional technology, it is necessary to detect the light direction in the image, and the precision of that detection has a large impact. Further, because it is presumed that light is coming from only one direction, the conventional technology cannot be suitably adopted when there are a plurality of lights, which is often the case in natural images. In other words, with the conventional technology, not only is it not possible to detect a plurality of lighting directions (the lighting directions due to a plurality of lights (light sources)), there is also a risk that the precision with which the light is detected will significantly worsen if the lighting direction partially changes. Thus, with the conventional technology there is a high degree of dependence on the image, and particularly in natural images, it is often the case that a suitable effect cannot be attained. There are other issues as well, such as the need to prepare lighting detection filters in advance.
The present invention was arrived at in light of these issues with the conventional technology, and it is an object thereof to achieve an image processing device, an image processing method, a program, a storage medium, and an integrated circuit that do not require detection of the lighting direction as in the conventional technology and that by appropriately adding shadow to the image can achieve an increase the feeling of depth and the feeling of three dimensions in a processed image, regardless of the distribution of the lighting in the image (even if there are multiple lights). Another object of the invention is to provide an image processing device, an image processing method, a program, a storage medium, and an integrated circuit that appropriately add light to an image in order to further increase the feeling of depth and the feeling of three dimensions in the processed image.